If you're a foreign resident in Japan wondering how to switch SIM providers, you're not alone. Whether your current plan is too expensive, your data runs out too quickly, or you simply want better English support, switching is absolutely possible — and often straightforward once you know the steps. This guide walks you through the entire process, including the important MNP number port, what documents to prepare, and which providers are more foreigner-friendly.
What Is MNP and Why Does It Matter?
MNP stands for Mobile Number Portability. It is the system that lets you keep your existing Japanese phone number when you move to a new carrier. If keeping your current number is important to you — and for most people it is, since your number may be linked to bank accounts, apps and contacts — then you need to follow the MNP process.
If you don't mind getting a completely new number, you can simply cancel your old plan and sign up fresh with a new provider. However, note that changing your number can be disruptive, especially for apps like LINE or services that use SMS verification.
Step-by-Step: How to Switch SIM Providers in Japan as a Foreigner
Step 1 – Check Your Current Contract
Before anything else, look at your current plan for two things:
- Contract period and cancellation timing: Some plans (especially from the big three carriers — docomo, au, SoftBank) have fixed contract periods. Cancelling outside a specific window may mean an early termination fee. Check your contract or log in to your account online to confirm.
- Any outstanding payments: If you are still paying off a handset in instalments, that balance usually continues even after you switch providers. Settle or confirm this before moving.
Plans and fees vary and change regularly, so always confirm the latest cancellation conditions directly on your current provider's official website or by calling their customer support.
Step 2 – Request Your MNP Reservation Number (MNP予約番号)
To port your number, you need to request an MNP reservation number from your current provider. You can usually do this:
- Online through your My Page account
- By calling customer service
- In store (though this can take longer)
This number is valid for a limited period (typically around 15 days — confirm with your provider). You must use it to complete the sign-up with your new provider before it expires.
Note: As of 2024, Japanese law has made it easier and faster to get an MNP reservation number, and some carriers now offer a one-stop MNP process. Check your current provider's website for the latest procedure.
Step 3 – Choose Your New Provider
This is where many foreigners hit a wall. The big three carriers (docomo, au, SoftBank) often require a Japanese credit card and can involve complex Japanese-language procedures. Fortunately, there are more foreigner-friendly options:
| Provider | Japanese Credit Card Required? | Language Support | Notes |
|---|---|---|---|
| GTN Mobile | No | Multilingual | Accepts residence card; flexible payment options |
| Mobal | No | English | No Japanese bank account required; English support |
| docomo / au / SoftBank | Usually yes | Japanese mainly | Wide coverage; can be harder for newcomers |
| Other MVNOs (e.g. IIJmio, mineo) | Often yes | Japanese mainly | Affordable; check individual requirements |
When comparing providers, look at these factors:
- Monthly price and data allowance
- Whether a Japanese credit card or bank account is required
- Voice calls included, or data-only
- Contract length and cancellation conditions
- English or multilingual customer support
- Network coverage in your area
Plans and prices change frequently. Always check the latest offerings on each provider's official website before deciding.
Step 4 – Prepare Your Documents
For most contract SIMs in Japan, you will need:
- Residence card (在留カード, Zairyu Card) — this is the standard ID for foreign residents
- Japanese address — required for the SIM to be delivered or registered
- Your MNP reservation number — if you are porting your number
- Payment method — credit card, debit card, or bank account depending on the provider
Some foreigner-friendly providers like GTN Mobile and Mobal do not require a Japanese credit card, which makes the process much easier if you are still getting settled.
Step 5 – Apply with Your New Provider
Most MVNOs and foreigner-friendly providers allow you to apply online. The process typically involves:
- Selecting your plan
- Entering your MNP reservation number (if porting)
- Uploading a photo of your residence card
- Entering your address and payment details
- Waiting for your SIM card to arrive by post (usually a few days)
eSIM options are also becoming more common and can activate faster — check whether your new provider offers this and whether your phone supports it.
Step 6 – Activate Your New SIM and Cancel the Old One
Once your new SIM arrives, follow the activation instructions provided. If you used MNP, your number will transfer automatically at activation — your old SIM will stop working at the same moment. You generally do not need to separately cancel your old contract if you completed the MNP process correctly, but confirm this with both providers to be sure.
Costs to Expect When Switching
Switching SIM providers in Japan may involve some costs. These vary by provider and change over time, so treat this as a general guide and confirm current fees on official sites:
- Early termination fee: May apply if you cancel within a fixed contract period
- MNP transfer fee: Many providers have abolished this fee, but check with yours
- SIM card issuance fee: Some MVNOs charge a one-time fee for the physical SIM
- First month's fee: May be prorated or charged in full depending on the provider
Useful Tips for Foreign Residents
- If your Japanese is limited, prioritise providers with English or multilingual support — it makes troubleshooting much easier.
- Prepaid SIMs or eSIMs are a good stopgap while you sort out a long-term contract plan.
- Make sure your phone is SIM-unlocked before switching. Phones bought from a Japanese carrier may be locked. You can usually request an unlock online through your current carrier.
- Keep a note of your MNP reservation number's expiry date and move quickly once you have it.
- Apps like LINE are tied to your phone number — back up your account before switching to avoid losing your chat history.
Summary: Switching SIM Providers in Japan as a Foreigner Is Manageable
Switching SIM providers in Japan as a foreigner takes a few clear steps: check your current contract, get your MNP reservation number, choose a new foreigner-friendly provider, prepare your documents, apply, and activate. The process is more accessible than it used to be, especially with providers like GTN Mobile and Mobal that don't require a Japanese credit card and offer support in English.
Take your time comparing plans — data allowance, cost, contract flexibility and language support all matter. And remember, plans and prices change, so always confirm the latest details on each provider's official website. You've already taken the hardest step by looking into it. The rest is just following the checklist.